Inserted tooth milling cutter



Patented Oct. 8, 1946 'e INSERTEDy TOOTH MILLING CUTTER Edward O. Lowell, South Pasadena, Calif., as-v signor, byvmfes'ne assignments, to Lowell and VGrrayson Manufacturing Company, Monrovia, Calif., a corporation of California kApplication Juli 8,1943, seri-a1 No. 493,815-

This invention relates to milling cuttersof the inserted tooth type and lis particularly concerned with improvements in the inserted teeth and the means for locking and holding the same securely. lThe principal object of my invention is to provide a milling cutter of the type mentioned, in which the insertedV teeth I mayv be adjusted, removed, or replaced easily, and are arranged to be locked and held in place, so that they are eX- tremely'rigid and there is little likelihood of vibration, these features being particularly important where the inserted teethrare tipped with tungsten carbide, tungsten titanium carbide, or tungsten tantalum carbide, these materials being hard but not tough,land while possessing extraordinary resistance to wear are easilybroken down ifV subjected to; excessive vibration. o i A salient featurev ofv the millingjcutter of my invention consists in the provision Yof precision fiat contacting surfaces on the backs of the inserted teeth and the cooperating back walls of the slots, such contact together withk the secure wedge locking actionof interfitting serrations on `wedges.

teeth, because, even assuming accurate machining of the body and teeth, there was no guarantee of the desired rigidity and tightness if the wedges, or the slots to receive 'the same, were .not machined just as accurately as the rest of the unit. Hence, the importance in the 'elimination of theof wedges was objectionable because of thedifiiculty of loosening'the same when adjustment or removal of vteeth was necessary. The serrations provided on the teeth for wedgingly locking the same are preferablyof a form providing maxiimum thrust of the tooth against theback wall of the slot to maintain the precision flat surfaces infirm contact, and yet when the screw, or screws, employed for holding the tooth are loosened there is nothing to interfere with the vquickfaiid easy adustment or removalv of the the front faces of the inserted teeth land 'the front walls of the slots making for the best possible-rigidity and eliminating danger ,of vibra-'- o,

tionof the insertedvteethA during operation. In

manyfearlier designs, intertting serration's were required on thebacks. of the inserted .teeth and the back walls of the slots,V` and, of course, it is well known that serrations cannotbe produced' as accurately as fiat surfaces; and', asia result, the contact between the teeth and the walls of the slots was inclined to be morefor less irregular, and, as a result, the teeth'lacked' rigidity' and were subject to more or less vibration in operation.

Another salient feature ofthe ymillingcutter of my invention is the elimination of the con;- ventional wedgeheretofore employed, usually at least one foreach inserted toothgthe.y inserted.Y

teeth, in accordance with my invention,.relying upon the interfitting serrations onV the front faces of the teeth andthe front'walls of the`slots lfor the Wedging action, thus simplifyingr the machining and reducing the number of parts required,

so ras to realize an important saving in cost,

while in addition reducing ,theamount of material required to be cut away from the body,Ak

and' accordingly strengthening the structure as a Whole and increasing rigidity and reducing likelihood of vibration. Obviously, Where wedges were required, therewas introduced. an addi-A tooth.

The invention is illustrated in the accompanying drawing, inwhich- Figure 1 isa side view of a millingcutter made in accordance with my invention, showing one of the inserted teeth in section to better illus.-

, trate 'the construction;

f Fig. y2 is an edge view showing two of the in- V'sertedteeth, one in front elevation and the other in end elevation, and

Fig. 3v isr a fragmentary side elevational View cfa-:milling cutter showingla modified or alternative construction `for the inserted teeth.

Similar reference numerals are applied to corresponding parts throughout the views.A

Referring first to Figs, 1 and 2, the reference numeral l0 designates the body'of a milling cutterhaving the usual center hole II and key slot I2. are provided in the peripheral .portion of the body in Aequally circumferentially' spaced relation tofreceive the inserted teeth i4, in accordance with my inventionfWhere a positive or negative rake angle or helix angle for the teeth I4 is desired, instead of .the neutral angle shown,

n the slots I3 may be inclined withrespect to the' radii or the axis accordingly, and, of course, this? same observation applies in regard to the other form illustrated in Fig. 3. The periphery of the -body is cutaway in front of each slot I3, as at 15,101` chip clearance, but the peripheral portion I5 of the body behind each vslot is not cut away, whereby to providel precision flat bearing tional factor of possible error that might account for looseness and lack of rigidityof the surface at I'I for good rigid support 4of the inserted teeth I4, these .teeth being provided with Y precision flat back surfaces I8 for contacty with the iiat back walls I1 of the slots. AThe front wall y Furthermore, in many designs the use A plurality of. substantially radial slots I3 of each slot has wedge lock serrations I9 provided therein to interi-lt in wedge lock serrations provided in the front face of the tooth I4 inserted in the slot. The teeth lli are adapted to be inserted in the slots from either side of the body, the wedge lock serrations having a close working nt. Consequently, after the teeth have become worn and require regrinding, the teeth can be removed and replaced one or more serrations removed from the original setting and .then fastened in the new setting. A pair of set screws 2l is provided in each tooth threaded in holes 22 parallel to one another and to the nat back face i8 of the tooth and the serrated front face 2B but substantially at right angles to the direction of said serrations, and these screws are provided with sockets 23 in their outer ends for application of a wrench, and are arranged to be tightened against the ilat inner end wall 24 of the slot. In the tightening of the screws the slight clearance in the intertting serrations i9 and 2li is taken up and the tooth is forced bodily against the back wall I1 of the slot with great pressure, and the tooth is therefore held rmly in place with great rigidity and there is no danger of excessive vibration vduring operation. I refer to these serrations as of the buttress type because of the resemblance to the shape of buttress threads, but Want to point out that whereas a buttress thread exerts force with minimum wedging and friction in relation to screw pressure, the serrations iQ-Z are intended -to give the opposite eiect and provide maximum wedging` and :friction in relation to the force exerted by the set screws. Centrifugal force is also an important factor tending to tighten the inserted teeth and make for greater rigidity and, incidentally, greater safety. The flat face contact at ll-l3 is particularly irnportant from the standpoint of rigidity, because, as previously stated, flat surfaces such as these may be produced very accurately, whereas it is not practical to cut the serrations as accurately, and in many previous constructions which required the provision of intertting serrations on the backs of the teeth and the back walls of the slots, the contact between the teeth and the slots was suiiiciently irregular to result in vibration during operation. The flat surface contact taken together with the wedge locking action reduces to a minimum the likelihood of vibration during operation, and that is particularly important where the teeth are tipped, as indicated at 25, with a cemented carbide cutting edge member, because .these materials are a product of powder metallurgy and although they possess extraordinary resistance to wear they are easily broken down when subjected to excessive vibration or not supported with sufficient rigidity.

The wedge lock serrations i9 and 2E) are of the ibuttress type, but, as shown in Fig. 3, I may employ serrations i9' and 2D of conventional design. The tooth insert I4 illustrated, it will be understood, is otherwise of the same construction as the tooth inserts i4 of Figs. 1 and 2, having set screws 2| threaded therein to engage the flat bottom surface 24 of the slot i3 and cause the flat back surface lI8 on the tooth to engage the iiat back wall Il of the slot.` The construction of Fig. 3 will accordingly give substantially the same results and advantages as that shown 'in Figs. 1 and 2.

It is believed therforegoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn with a view to covering all legitimate modiiications and adaptations.

I claim:

1. A milling cutter of the inserted tooth type, comprising a rotatable body member provided with a substantially radial tooth receiving slot, a tooth in said slot, interfitting serrations on a wall of the slot and the adjacent face of the tooth, said serrations extending generally longitudinally of the axis of rotation of the body, whereby the tooth is insertible and removable by movement laterally with respect to the body, and one or more fastening screws threaded in through-holes provided in the tooth in transverse relation to said serrations, said screws being threadable into engagement with the inner end of the slot to force the interiitting serrations into wedging engagement.

2. A milling cutter of the inserted tooth type, comprising a rotatable body member provided with a substantially radial tooth receiving slot, a tooth fitting closely in said slotintertting serrations on the front wall of the slot and the front face of the tooth, said serrations extending generally longitudinally of the axis of rotation of the body, whereby the tooth is insertible and removable by movement laterally with respect to the body, the back wall of the kSlot and the abutting back face of the tooth being flat and in a plane parallel to the plane of the serrations, and one or more fastening screws which with the intertting serrations comprise the sole fastening means for the tooth, said screws acting between the body and tooth by abutment with the one and threaded engagement in the other and disposed ,substantially radially relative to the body -in transverse relation to said serrations, whereby when said screws are tightened the tooth is placed under end thrust radially relative to the body member and clamped in its adjusted position by Wedging engagement of the intertting serrations, and the at back face on the tooth is forced into tight engagement with the flat back wall of the slot.

3. A milling cutter of the inserted tooth type', comprising a rotatable body member provided with a substantially radial tooth receiving slot, a tooth in said slot, intertting serrations on the front Wall of the slot and the front face of the tooth, said serrations extending generally longitudinally of the axisk of rotation of the body, whereby the tooth is insertible .and removable by movement laterally with respect to the body, the back wall of the slot. and the back face of the 5 tooth being fiat and in a plane parallel to the plane of the serrations, and one or more fastening screws threaded in through-holes provided in the tooth in transverse relation to said serrations, said screws being threadableinto .engagement 0 with the inner end of the slot to force the interfitting serrations into Wedging engagement and force the nat back face on the tooth into tight engagement with the nat back wall of the slot.

4. A mining cutter of the inserted tooth type,l

comprising a body member having substantially radialtransverse slots, cutter insert members disposed in and closely fitting said slots, said cutter members having wedge-shaped serrations transversely in the front face thereof for adjustable 0 slidable engagement in complementary serrations provided generally longitudinally of the aXis of rotation of the body in the front wallof the slots adapted to be wedgingly engaged upon slight suby stantially radial movement of the cutter mem'- bers relative to the body member, the back wall 5 of the slots and the abutting back face of the cutter members being flat and parallel to the plane of the front Wall of the slots and a tightening screw means within each cutter mem-ber cooperating with the lbody to cause such radial movement of the cutter members for wedging engagement of the aforesaid serrations and clamp said cutter member in place.

5. A milling cutter of the inserted tooth type, comprising a body member having substantially radial transverse slots, cutter insert members disposed in and closely tting said slots., said cutter members having Wedge-shaped serrations transversely in the front face thereof for adjustable slidable engagement in complementary serrations provided generally longitudinally of the axis of rotation of the body in the front wall of the slots adapted to be Wedgingly engaged upon slight substantially radial movement of the cutter members relative to the body member, the back wall of the slots and the abutting back face of the cutter members being flat and parallel to the plane of the front wall o the slots and means for forcing the cutter members substantially radially outwardly with respect to said body member to cause Wedging engagement of the aforesaid serrations, whereby to secure the cutter members in substantially immovable position.

EDWARD O. LOWELL. 

